MCAT BIology Muscles and Flashcards
___ refers to reducing the angle of the joint
Flexing
___ refers to increasing the angle of the joint
Extending
___ fers to moving away from the body’s modiline
Abducting
____ refers to moving toward the body midline
Adducting
The point on the boner where a muscle attaches it called the __
origin of that muscle
The point where the muscle attaches on the bone more distant from the center of the body is referred to as the muscle’s __
insertion
___ filaments are attached to Z lines but not __ filaments
Thin filaments (actin) are attached to Z lies, but thick filaments are not
The region of a myofibril with only thick filaments only seen in resting sarcomeres is referred to as__
H zone
During muscle contraction, do the thin and thick filaments shorten?
No, the thin and thick filaments slide across each other to shorten the sarcomere without themselves changing in length
Binding of ____ is necessary for the release of actin by the myosin head
a new ATP molecule
Contraction of a muslce only occurs when ___ increases
cytoplasmic (Ca2+) increases
What protein is responsible for ATP hydrolysis during muscle contraction?
Myosin is the protein with the ATPase activity
The ___ is the synapse between an axon terminus (synaptic knob) and a myofiber
Neuromuscular junction (NMJ)
The postsynaptic membrane ( the myofiber cell membrane) is known as the __
motor end plate
What are the two ways that the nervous system can increase the force of contraction?
- Motor unit recruitment
2. Frequency summation
The liver picks up lactic acid in the bloodstream from the muscles and turns it into ___
pyruvate
What is the cause of rigor mortis?
Results from complete ATP exhaustion, without ATP, myosin heads cannot release actin, and the muscle can neither contract nor relax
These are the fibers that allow marathoners and long distance cyclists to run or bike for hours at a time
Type 1 slow twitch fibers
Type ___ fast twitch fibers have more mitochondria than ___ and are thus more fatigue resistant
Type 2A fast twitch fibers have more than Type 2B
___ are the fibers needs for explosive force like pole vault and dunking
Type 2B
The function of T tubules in both cardiac and skeletal muscle is to
transmit APs into the interior of the large, thick cell
___ is a functional syncytium not a structural synctium
Cardiac muscle cells ,because they are uninucleated but they are interconnected and allow AP’s to propagate through them
In cardiac muscle cells some of the required calcium comes from __
extracellular environments through the voltage-gated calcium channels
The voltage-gated calcium channels cause the cardiac AP to have a distinctive plateau, what are the two significant things of this plateau phase?
- longer duration of contraction facilitates ventriular emptying (better ejection fraction)
- Longer refractory period prevents disorganized transmission of impulses through the heart, and makes summation and tetanus impossible
Smooth muscle does not have __ because the cells are much smaller and narrower than skeletal muscle cells and cardiac muscle cells
T-tubules
Both smooth muscle and cardiac muscle are __
functional syncytium
Thick and thin filaments are not organized in sarcomeres in smooth muscle, they are __
dispersed in the cytoplasm, thats why they are smooth
The __ is not present in smooth muscle, smooth muscle contraction is regulated by calmodulin and myosin light-chain kinase (MLCK)
troponin-tropomyosin
The __ and ___ regulate smooth muscle contraction
Calmodulin, and myosin light-chain kinase
The axial skeleton consists of ___,___, and the__
skull, vertebral column, and the rib cage
All bones other than skull, vertebral column, and rib cage are part of the ___
appendicular skeleton
The main ingredients in ground substance of connective tissue is __
proteoglycans
___ bones are the location of hematopoiesis
Flat bones such as the scapula, ribs, and bones of the skull
Shaft of a long bone is the ___
diaphysis
The flared end of long bones are __
epiphysis
The diaphysis of long bones is a tube composed only of ___
compact bone
Bone is composed of two principal ingredients ___ and ___
collagen and hydroxyapetite
The basic unit of compact bone structure is the ___
osteon (referred to as Haversian system)
joints are lined by hyaline cartilage known as __
articular cartilage
___ connect bones to other bones
Ligaments
___ connect bones to muscles
Tendons
Immovable joints are called
Synarthroses
Slightly movable joints are called__
amphiarthroses
Freely movable joints are called
Diarthroses
Most bone growth occurs by ___ in which hyaline cartilage is produced and then replaced by bone
Endochondral ossification
___ refers to the synthesis of bone from an embryonic tissue called mesenchyme
Intramembranous ossification
___ is a disk of hyaline cartilage that is actively being produced by chondrocytes during growth in long bones
Epiphyseal plate
